I’m not sure what you mean by odds being manipulated. The bookmaker will generally adjust odds to where the money is being placed. Example, in American football if a team opens up as a 7 point favorite and betters put more money on the underdog than the favorite, the line gets smaller so more will take the favorite. Generally the opening line is what the book will think half the betters are willing to place on the favorite, and half on the underdog. Doesn’t always work out that way which is why you see lines move.
Various forms of this have been practiced in traditional casinos for almost a century with increasing sophistication, it’s a well-established art by now.
Also not sure what you mean by winners